Preparation And Electrodialysis Desalination Performance Of PVDF-based Cation Exchange Membrane

Due to the poor stability and high energy consumption of traditional heterogeneous cation exchange membranes,homogeneous cation exchange membranes rely heavily on imports and expensive.Therefore,the purpose of this paper is to develop a preparation technology of homogeneous cation exchange membrane with low cost and excellent performance.First,aiming at the problems of poor stability and high energy consumption of traditional heterogeneous cation exchange membranes.In this paper,a strategy of blending PVDF with styrene was proposed,and then PVDF/styrene cation exchange membrane was prepared by postsulfonation method.The morphology and structure of the membrane were characterized by SEM.At the same time,the effects of sulfonation time and sulfonation temperature on the properties of the membrane were investigated.With the extension of sulfonation time,the content of sulfonic acid group on the surface of the membrane increased gradually.When the sulfonation temperature was 70? and the sulfonation time was 7 h,the PVDF/styrene cation exchange membrane showed excellent electrochemical performance,with an IEC of 2.09 mmol/g,a water absorption of 26.5%,an ion selective transmittance of 90.3%and a tensile strength of 20.86 MPa.Secondly,aiming at the problem of environmental pollution caused by the use of concentrated sulfuric acid in the sulfonation process.The homogeneous cation exchange membrane of PVDF was prepared by free radical polymerization using sodium styrene sulfonate(SSS)as functional monomer,DVB as cross-linking agent and AIBN as initiator.The morphology and structure of the membrane were characterized by SEM,FT-IR and TGA.At the same time,the effects of SSS and DVB addition on the performance of the membrane were investigated.With the increase of the amount of SSS,the IEC,ion selective transmittance and other properties of the membrane are also increasing.When the addition of DVB and SSS was 10 wt%and 38 wt%respectively,the PVDF/PSSS cation exchange membrane showed excellent electrochemical performance,with IEC of 2.18 mmol/g,water absorption of 21.23%,ion selective transmittance of 95.2%and tensile strength of 16.2 MPa.Finally,the electrodialysis desalination performance of PVDF/PSSS uniform cation exchange membrane was investigated.With the increase of the volume of the desalination chamber,the energy consumption was decreasing.The results show that when the initial concentration of NaCl solution is 0.6 mol/L,the desalination rate is 98.6%,the energy consumption is 4.68 kW·h/Kg,and the concentration ratio is 90.24%.